1. Field of the Invention
The present invention relates to a Light Emitting Diode (LED) and, more particularly, to an LED package having a simple configuration with superior heat radiation efficiency, and a fabrication method thereof.
2. Description of the Related Art
A light emitting diode (LED) is a semiconductor device for generating various colors of light in response to current application. The colors generated from the LED are determined by the chemical substances constituting the semiconductor of the LED. Such an LED has various merits such as a long lifetime, low power, excellent initial driving characteristics, high resistance for vibration and high tolerance for frequent power on/off compared to a light emitting device based on filament, and thus there has been a steadily increasing demand for the LEDs.
LEDs are recently adopted as backlights for lighting devices and large sized Liquid Crystal Displays (LCDs), which require large outputs, and accordingly the LEDs used therefor require especially excellent heat radiation capacities.
FIGS. 1 and 2 illustrate a conventional LED package mounted on a circuit board.
First, referring to FIG. 1, the LED package 1 has a heat slug 3 for seating the LED chip 2 thereon while functioning as a heat guiding means. The LED chip 2 receives electricity from an external source (not shown) through a pair of wires 7 and a pair of terminals 8. The upper part of the heat slug 3 including the LED chip 2 is encapsulated by an encapsulant 5 typically made of silicone, and a lens 6 is attached over the encapsulant 5. A housing 4 is formed around the heat slug 3 by general molding to support the heat slug 3 and the terminals 8.
Such an LED package 1 of FIG. 1 is mounted on a circuit board 10, which is a heat sink, to construct an LED assembly as shown in FIG. 2. At this time, a heat conducting pad 9 such as solder is interposed between the heat slug 3 of the LED package 1 and a metal heat radiating plate (not shown) of the circuit board 10, facilitating heat conductivity between them. In addition, the terminals 8 are also more stably connected to a circuit pattern (not shown) of the circuit board by the solder (not shown).
As described above, the LED package 1 shown in FIGS. 1 and 2 and the LED assembly with the LED package 1 mounted on the circuit board 10 are focused on effective discharge of the heat, i.e., heat radiation. That is, the LED package 1 has the heat sink, i.e., the heat slug 3 connected to the heat radiating plate of the circuit board 10 either directly or via the heat conducting pad 9 in order to absorb and discharge the heat generated from the LED chip 2. This allows the heat generated from the LED chip 2 to be mostly discharged via the heat slug 3 into the circuit board 10, and only a small amount of the heat to be discharged into the air through the surface of the LED package 1, i.e., through the housing 4 or the lens 6.
However, this conventional heat radiation structure is complicated and requires many components. Therefore, it is difficult to automate the manufacturing process of the LED package with assembly of many components, thus increasing the manufacturing time and costs.
FIG. 3 is a sectional view illustrating another conventional LED package.
The LED package shown in FIG. 3 is suggested in “SEMICONDUCTOR LIGHT-EMITTING DEVICE,” U.S. Patent Application Publication No. 2005/0057144 (published on May 17, 2005). In this LED device or LED package, a cup-shaped reflecting frame 2 is installed on a surface of the substrate 1 with circuit patterns 3 and 6 formed thereon, and an LED chip 4 is mounted in the cup-shaped portion and electrically connected to the circuit pattern 3. In the meantime, the reference numeral 7 represents phosphor, the reference numeral 8 represents diffuser and the reference numeral 9 represents resin.
The LED package with the above described configuration requires a fewer number of components than that of FIG. 1 and can be advantageously fabricated into a relatively simple configuration. However, the heat generated from the LED chip 4 is transferred to a circuit board 10 (not shown in FIG. 3, see FIG. 2) via a heat radiation path H, thus resulting in low heat radiation efficiency.